Review on Hanna Instruments HI38033 Total Hardness Test Kit by Phillip Hoover

Works well, although you have to follow (simple) instructions. I wish they had provided a laminated instruction card (I scanned it immediately for safekeeping). The plastic bottle fits but is too small in my opinion and the hole in the top of the lid is too small for accurate instillation. I don't use it and it works much better. It is important to measure the hardness - as far as I know there is no other way to do this. Forget the stripes - it's useless. If you have a water softener, you need this kit. In theory, hardness is related to conductivity, but this chemical system is more accurate.